Directional light emitters and electronic displays featuring the same

ABSTRACT

Methods, systems, and apparatus, including computer programs encoded on computer storage media, for changing a distributed mode loudspeaker&#39;s fundamental frequency. One of the systems may include a light emitting diode display that includes an array of pixels, each pixel including, for each color of multiple colors, a directional light emitter and a wide-angle light emitter, a first combination of all the directional light emitters configured to generate a first display image viewable within a first viewing angle, and a second combination of all the wide-angle light emitters configured to generate a second display image concurrently with the generation of the first display image that is viewable within a second viewing angle. The first display image is a different image than the second display image and the first viewing angle is a narrower viewing angle than, and included within, the second viewing angle.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 15/850,743, filed Dec. 21, 2017, now allowed. The contents ofthe prior application are incorporated herein by reference in theirentirety.

TECHNICAL FIELD

This disclosure relates to directional light emitters and displaysfeaturing directional light emitters, including light field displays anddual mode displays.

BACKGROUND

Many direct view flat panel displays generate images by selectivelymodulating a light intensity emitted by each pixel in an array acrossthe panel. In full color displays, each pixel is composed of differentlycolored subpixels (e.g., red, green, blue or cyan, yellow, magenta), thedisplay emitting varying amounts of colored light from each subpixelthat additively combine so that each pixel, as a whole, appears adesired color that is a combination of the subpixel light.

Some displays use light emitting diodes (LEDs), including inorganic ororganic LEDs, to generate an image. For instance, each subpixel caninclude a red, green, or blue LED to provide full color images.Typically, each LED emits light substantially isotropically into ahemisphere so that multiple viewers can view the same displayed imagefrom various locations about the display. For example, the LEDs can beLambertian emitters, where the relative intensity of light falls off asthe square of the cosine of the viewing angle as one moves off the axisnormal to the display. Indeed, a wide viewing angle (e.g., as much as170° in the horizontal viewing plane) is a desirable feature in manyapplications, such as displays used as large, wall-mounted televisions.

SUMMARY

Displays composed of arrays of small, directional light emitters aredisclosed. Each pixel (or subpixel, e.g., for color displays withspatially synthesized color) is composed of multiple emitters, eacharranged to direct light into different viewing directions. Suchdisplays can present different images when viewed from differentdirections.

For example, pixels composed of multiple directional emitters eacharranged to direct light into different viewing directions can be usedto form light field displays, in which each pixel (or each subpixel)selectively directs light into one or more discrete directions within anoverall viewing cone of the display (e.g., 170° or more in both thehorizontal and vertical directions). When viewed from differentdirections, light field displays can display different images. Forexample, light field displays can display images of the same object orscene but from different viewpoints depending on the location of theviewer. In some embodiments, light field displays can providestereoscopic 3D imagery, where different images of the same object orscene are presented to each of the viewer's eyes.

In some implementations, multiplexing techniques are used to increasethe resolution of a light field pixel. For example, pixels can bemanipulated to direct light from a light emitter into differentdirections at different moments during a single image frame. Forexample, pixels can include one or more actuable optical elements thatcan be manipulated to direct light into different directions. MEMSmirrors and/or variable lenses can be used for this purpose.

In some embodiments, the directional emitters are composed of resonantcavity emitters in which a small light source, such as a micro-lightemitting diode (μLED) is incorporated within an optical cavity thatenhances emission into a narrow range of angles. Alternatively, oradditionally, photonic crystal layers can also be used to inhibitpropagation of certain modes from an emitter, providing directionalemission.

Light field display pixels utilizing coherent light sources are alsocontemplated. For example, a light field pixel can introduce a variablephase shift across a coherent wavefront, selectively generating brightand dark diffractive maxima at different angular viewing positions.

In some embodiments, display pixels can include a combination ofdirectional and isotropic emitters. For example, each pixel can includeone or more directional μLEDs along with an isotropic-emission μLED.Such a display's pixel array can include directional light emitters thatgenerate a first image with a first, narrow, viewing angle, e.g.,viewable by a single viewer. Each pixel also includes a wide-angle lightemitter that generates a second image with a second, wider, viewingangle, e.g., viewable by multiple viewers. The first image may beviewable concurrently with the second image by only the single viewer,e.g., while the other viewers from the multiple viewers view the secondimage but cannot view the first image. This may enhance security,privacy, or both, for content included in the first image.

The directional light emitters can be co-located on the display withcorresponding wide-angle light emitters (e.g., a pixel region on thedisplay may include both a directional light emitter and a wide-anglelight emitter for a particular color used to generate a respectivepixel). Alternatively, a group of directional light emitters (e.g., allcolors for a respective pixel) can be located near a corresponding groupof wide-angle light emitters. The light emitters are sufficiently closetogether so that a viewer of the display perceives light emitted fromthe group of directional light emitters to come from the same locationon the display as the corresponding group of wide-angle light emitters.

In general, systems that include displays with directional emitters mayadjust an angle at which the display projects light from the directionallight emitters. For instance, the system can use eye-tracking todetermine a predicted angle at which a viewer is looking at the display.The system may use the predicted angle to determine an adjustment tosome or all of the directional light emitters in the display, e.g., aset of directional light emitters, and cause the display to adjust theangle at which light from the directional light emitters is projected,e.g., using beam steering. In some examples, the system causesadjustment of the directional light emitters while maintaining thedirection at which the wide-angle light emitters project light, e.g.,the wide-angle light emitters can be fixed.

A system may dynamically adjust content presented by the light emitters.For instance, the system may detect input indicating that the displayshould present a third image, using a second array of directional lightemitters that are separate light emitters from a first array ofdirectional light emitters, e.g., described above. In response, thedisplay may use the second array of directional light emitters togenerate the third image, e.g., which may be viewable by another viewer.The input detected by the system can include identifying entry of theperson in a room that includes the display, input received from acontrol device, or another appropriate form of input. The presentationof two or more images concurrently by the display may reduce thehardware footprint necessary to concurrently present the images, mayreduce the power necessary to generate the images, or both.

In some implementations, the system can dynamically adjust contentpresented by the light emitters based on a determination of whichcontent should be presented by wide-angle light emitters. For instance,the system may initially present first content in one or more firstimages generated by the directional light emitters and second content inone or more second images generated by the wide-angle light emitters.The system may determine that the wide-angle light emitters shouldpresent the first content and the directional light emitters shouldpresent the second content, e.g., in response to receipt of user inputor determining a context change. The context change may be entry ofanother person into a room that includes the display and a determinationto present the first content to the other person in addition to a personwho was first viewing the first content while presenting the secondcontent to the original viewer of that content.

In general, in a first aspect, the invention features a light emittingdevice that includes a substrate supporting a first light emittingelement and a second light emitting element, the first light emittingelement being configured to emit, in a first principal direction, lightin a first wavelength band and the second light emitting element beingconfigured to emit, in the first principal direction, light in a secondwavelength band different from the first wavelength band, each lightemitting element including: a light emitting diode layer, extending in aplane perpendicular to the first direction, having a thickness of 10microns or less in the first direction and a maximum lateral dimensionof 100 microns or less orthogonal to the first direction, the lightemitting diode layer including a semiconductor material; and one or morelayers configured to enhance an optical mode (or one or more opticalmodes) of the light emitted in the corresponding first or secondwavelength band perpendicular to the plane and/or suppress an opticalmode (or one or more optical modes) of the light emitted in thecorresponding first or second wavelength band in the plane.

Embodiments of the system can include one or more of the followingfeatures.

The light emitting diode layer of each light emitting element caninclude an active layer, a hole transport layer, and an electrontransport layer.

The one or more layers configured to enhance/suppress optical mode(s)can include, for at least one of the light emitting elements, at leasttwo layers positioned on opposite sides of the diode layer, and the atleast two layers can form a resonant optical cavity configured toenhance the optical mode(s) of the light emitted in the correspondingone of the first or second wavelength bands perpendicular to the plane.For at least one of the light emitting elements, the two layers can bereflective at the corresponding one of the first and second emittedwavelengths. At least one of the reflective layers can include aDistributed Bragg Reflector and/or can provide anelectrically-conductive contact. One of the two layers can be partiallytransmissive at the corresponding one of the first and second emittedwavelengths.

The one or more layers configured to enhance/suppress optical mode(s)can include, for at least one of the light emitting elements, a photoniccrystal layer positioned adjacent to the diode layer, the photoniccrystal layer including a two dimensional photonic crystal structurethat is configured to suppress the optical mode(s) of the light emittedin the corresponding one of the first and second wavelength bands in theplane.

For at least one of the light emitting elements, the light emittingdiode layer can have a thickness of 10 μm or less, 5 μm or less, or 3 μmor less in the first direction and/or a maximum lateral dimension of 50μm or less, 20 μm or less, 10 μm or less, orthogonal to the firstdirection.

For at least one of the light emitting elements, the light emittingdiode layer can include an inorganic crystalline semiconductor material,such as a III-V semiconductor material or a II-CI semiconductormaterial. The light emitting diode layer can additionally oralternatively include an organic semiconductor material, such aspoly(p-phenylene vinylene).

The first and/or second wavelength band of the corresponding lightemitting element can include visible light (e.g., 390 to 700 nm).

The first and/or second light emitting element can be configured to emitlight in a corresponding first principal direction with a divergenceangle 15° or less, 10° or less, 8° or less, 5° or less, 3° or less, 2°or less, or 1° or less.

In general, in a further aspect, the invention features a light emittingdevice, including a plurality of light emitting elements each configuredto emit light in a first wavelength band in a first direction, eachlight emitting element including a light emitting diode layer extendingin a plane perpendicular to the first direction and configured toproduce light of the first wavelength, each light emitting elementfurther including one or more layers configured to enhance an opticalmode (or one or more modes) of the light emitted in the first wavelengthperpendicular to the plane or suppress an optical mode (or one or moremodes) of the light emitted in the first wavelength in the plane; andone or more light directing elements positioned to receive the lightemitted by the plurality of light emitting elements and direct the lightfrom each of the light emitting elements into a corresponding one of aplurality of different principal directions.

Embodiments of the system can include one or more of the followingfeatures.

The plurality of light emitting elements can be arranged as an array(e.g., one dimensional array, two dimensional array).

Each light directing element (including e.g., a refractive, diffractive,or reflective element) can be positioned to receive the light emitted bya corresponding light emitting element of the plurality of lightemitting elements and direct the received light into a corresponding oneof a plurality of different principal directions. Alternatively, oradditionally, each light directing element can be positioned to receivethe light emitted by more than one of the plurality of light emittingelements and direct the received light from each of the more than onelight emitting elements into a corresponding one of a plurality ofdifferent principal directions.

The one or more of the light directing elements can be a diffractiveoptical element arranged to diffract incident light from each of thelight emitting elements into the corresponding one of the differentprincipal directions. The one or more of the light directing elementscan be a mirror arranged to reflect incident light from each of thelight emitting elements into the corresponding one of the differentdirections. The mirror can be actuable. The one or more of the lightdirecting elements can be a lens arranged to refract incident light fromeach of the light emitting elements into the corresponding ones of thedifferent principal directions. The lens can be deformable.

The light emitting device can further include an actuator arranged tovary a relative position between the plurality of light emittingelements and the light directing element. The light directing elementcan direct light received from a light emitting element into differentprincipal directions depending on the relative position between thelight directing element and the light emitting element.

The light emitting device can further include a second plurality oflight emitting elements configured to emit light in a second wavelengthband different from the first wavelength band in the first direction.

The one or more layers of the light emitting device can include twolayers positioned on opposite sides of the diode layer, the two layersforming a resonant optical cavity configured to enhance the opticalmode(s) of the light emitted in the first wavelength perpendicular tothe plane. Additionally, or alternatively, the one or more layers caninclude a photonic crystal layer positioned adjacent to the diode layer,the photonic crystal layer including a two dimensional photonic crystalstructure configured to suppress the optical mode(s) of the lightemitted in the first wavelength in the plane. Additionally, oralternatively, the one or more layers can be configured to enhance theoptical mode(s) of the light emitted in the first wavelengthperpendicular to the plane and suppress the optical mode(s) of the lightemitted in the first wavelength in the plane.

The diode layer can include an active layer, a hole transport layer, andan electron transport layer.

The light emitting device can be incorporated into a light fielddisplay.

A light field display can include a plurality of the light emittingdevices, the light emitting devices being arrayed in a plane as aplurality of pixels each emitting a light field of a first color. Thelight field display can further include a second plurality of lightemitting devices configured to emit light at a second wavelength and athird plurality of light emitting devices configured to emit light at athird wavelength, the first, second, and third wavelengths beingdifferent, in which the light emitting devices are arranged to form anarray of pixels, each pixel including three subpixels each having alight emitting device that emits light at the first, second, or thirdwavelengths, respectively.

In general, in a further aspect, the invention features a light fielddisplay for displaying a series of image frames to one or more viewers,the light field display including a plurality of light field pixels,each light field pixel including a plurality of light emitting elements,each light emitting element being configured to emit substantiallycollimated light, in which each light field pixel selectively emitslight from each light emitting element into one or more of a pluralityof different viewing directions during a single image frame duringoperation of the light field display; and an electronic controller incommunication with the plurality of pixels, the electronic controllerbeing programmed to cause each light field pixel to direct light intoone or more of the plurality of different viewing directions such that aperspective of a displayed image varies according to the viewingdirection.

Embodiments of the system can include one or more of the followingfeatures.

The substantially collimated light can form a light beam with adivergence angle 15° or less, 10° or less, 8° or less, 5° or less, 3° orless, 2° or less, or 1° or less.

Each of the light emitting element can include a light emitting diodearranged in a resonant cavity. Each light emitting diode can have athickness of 10 microns or less in the first direction and a maximumlateral dimension of 100 microns or less.

Each of the light emitting elements can include a light emitting diodecoupled to a two dimensional photonic crystal.

Each light field pixel can further include one or more light directingelements (including, e.g., a refractive optical element, a diffractiveoptical element, or a reflective optical element). The one or more lightdirecting element can each be switchable between two or moreconfigurations in which the light directing element directs light from alight emitting element into a different viewing direction. Each of theone or more light directing elements can have a variable optical powerand can be switchable between different optical states by varying theoptical power. For example, each of the one or more light directingelements can include a deformable lens or an actuable mirror.

The one or more light directing element can each be switchable betweenthe two or more configurations during a single frame of the light fielddisplay.

For each light field pixel, light from a single light emitting elementcan be sequentially directed into multiple viewing directions during asingle frame. Additionally, or alternatively, light from a single lightemitting element can be directed to a single corresponding viewingdirection during each frame.

Each light field pixel can include three light field sub-pixels eachconfigured to emit light of a different color (e.g., red, green, or bluelight, or either cyan, magenta, or yellow light).

The light field display can have four or more, or 10 or more, viewingdirections in at least one viewing plane.

The electronic controller can be programmed to control the pixels todisplay a different perspective of a common scene in each of thedifferent viewing directions. The different perspectives can beperceivable as a stereoscopic image of the common scene by a viewer.

In general, in a further aspect, the invention features a light fielddisplay for displaying a series of image frames to one or more viewers,the light field display including: one or more coherent light sources; aplurality of light field pixels, each light field pixel arranged toreceive light from one of the coherent light sources, each light fieldpixel including a plurality of phase-shifting elements, each phaseshifting element being arranged in a path of a portion of the receivedlight and configured to variably shift a phase of the received lightrelative to the other phase-shifting elements of the light field pixelto produce phase-shifted light, the light field pixel being configuredto emit the phase-shifted light from the phase shifting elementscollectively as emitted light so that, during operation of the lightfield display, the light field pixel selectively directs light into oneor more of a plurality of different viewing directions during a singleimage frame; and an electronic controller in communication with theplurality of light field pixels, the electronic controller beingprogrammed to cause each light field pixel to direct light into one ormore of the plurality of different viewing directions such that aperspective of a displayed image varies according to the viewingdirection.

Embodiments of the system can include one or more of the followingfeatures.

The coherent light sources can be laser light sources (e.g.,semiconductor laser light sources).

The coherent light sources can include at least one source of red light,at least one source of green light, and at least one source of bluelight. The coherent light sources can include at least one source ofcyan light, at least one source of magenta light, and at least onesource of yellow light.

The light field display can include a waveguide coupling the at leastone coherent light source to the light field pixel. For example, thewaveguide can be a fiber waveguide.

The multiple light field pixels can be coupled to a single one of thecoherent light sources.

Each light field pixel can include a plurality of sub-pixels, eachsub-pixel arranged to receive light from a differently colored one ofthe one or more coherent light sources.

Each phase-shifting element can include an electrooptic material.

Each light field pixel can include a plurality of outcoupling elementseach coupled to a corresponding phase-shifting element, the outcouplingelement being configured to receive phase-shifted light from thecorresponding phase-shifting element and emit the phase-shifted lightfrom the light field pixel. Each outcoupling element can include agrating, a lens, or a mirror. Each outcoupling element can be configuredto direct light from the corresponding phase-shifting element in acommon direction.

Each light field pixel can include a spatial phase modulator includingan array of the phase-shifting elements.

The light field pixel can further include one or more optical elementsarranged to expand and collimate light from the at least one coherentlight source to illuminate the spatial phase modulator.

In general, one innovative aspect of the subject matter described inthis specification can be embodied in a system that includes an array ofpixels, each pixel including, for each color of multiple colors, adirectional light emitter and a wide-angle light emitter, a firstcombination of all the directional light emitters configured to generatea first display image viewable within a first viewing angle, and asecond combination of all the wide-angle light emitters configured togenerate a second display image concurrently with the generation of thefirst display image that is viewable within a second viewing angle, inwhich the first display image is a different image than the seconddisplay image and the first viewing angle is a narrower viewing anglethan, and included within, the second viewing angle. Other embodimentsof this aspect include corresponding computer systems, methods, andcomputer programs recorded on one or more computer storage devices, eachconfigured to perform the actions of the operations. The computer systemmay include one or more computers and can be configured to performparticular operations or actions by virtue of having software, firmware,hardware, or a combination of them installed on the system that inoperation causes or cause the system to perform the actions. One or morecomputer programs can be configured to perform particular operations oractions by virtue of including instructions that, when executed by dataprocessing apparatus, cause the apparatus to perform the actions.

In general, one innovative aspect of the subject matter described inthis specification can be embodied in methods that include the actionsof generating, by a light emitting diode display using a plurality ofwide-angle emitters, a first display image viewable in a first viewingangle; and generating, by the display using a plurality of directionalemitters concurrently with generation of the first display image, asecond display image that is a different image than the first displayimage and is viewable in a second viewing angle that is a smallerviewing angle than, and included within, the first viewing angle. Otherembodiments of this aspect include corresponding computer systems,apparatus, and computer programs recorded on one or more computerstorage devices, each configured to perform the actions of the methods.A system of one or more computers can be configured to performparticular operations or actions by virtue of having software, firmware,hardware, or a combination of them installed on the system that inoperation causes or cause the system to perform the actions. One or morecomputer programs can be configured to perform particular operations oractions by virtue of including instructions that, when executed by dataprocessing apparatus, cause the apparatus to perform the actions.

The foregoing and other embodiments can each optionally include one ormore of the following features, alone or in combination. The array ofpixels may include groups of color specific sub-pixels, each of thecolor specific sub-pixels including a directional light emitter and awide-angle light emitter. The array of pixels may include groups ofviewing angle specific sub-pixels, each of the viewing angle specificsub-pixels including, for each color in a group of colors, a lightemitter specific to the corresponding viewing angle and for therespective color. The group of colors may consist substantially of red,green, and blue. The group of colors may consist substantially of cyan,magenta, yellow, and black. Each of the directional light emitters maybe adjacent to another directional light emitter of a different color.The system may include a directional pixel-subset that includes, foreach color in a group of colors, a respective directional light emitter;and a wide-angle pixel-subset that includes, for each color in the groupof colors, a respective wide-angle light emitter, each directionalpixel-subset included in the light emitting diode display adjacent to acorresponding wide-angle pixel-subset that has the same position in thearray of pixels as the directional pixel-subset. Each of the directionallight emitters may be adjacent to a wide-angle light emitter of the samecolor.

In some implementations, the system may include an electronic controllerto change a viewing angle for the directional light emitters. Theelectronic controller may include an array of light directing elements.The electronic controller may include one light directing element foreach of the directional light emitters. The electronic controller mayinclude one light directing element for each group of the directionallight emitters. The system may include a communication module to receiveviewing angle adjustment data and provide the viewing angle adjustmentdata to the electronic controller. The system may include aneye-tracking component to determine eye movement data for a viewer,generate viewing angle adjustment data, and provide the viewing angleadjustment data to the electronic controller to change the viewing angleof the directional light emitters.

In some implementations, generating, by the display using the pluralityof directional emitters concurrently with generation of the firstdisplay image, the second display image may include generating, by thedisplay using the plurality of directional emitters after generation ofthe first display image, the second display image for presentationconcurrently with presentation of the first display image. A method mayinclude changing, by the display using an electronic controller, thesecond viewing angle of the second display image. Changing the secondviewing angle of the second display image may include adjusting, by theelectronic controller, one or more light directing elements to changethe second viewing angle of the second display image. A method mayinclude receiving viewing angle adjustment data; and generating, by theelectronic controller, angle adjustment commands using the viewing angleadjustment data. Changing, by the electronic controller, the secondviewing angle of the second display image may include adjusting, by theelectronic controller, one or more light directing elements using theangle adjustment commands. Receiving the viewing angle adjustment datamay include capturing, by a camera, one or more images; and determining,by an eye-tracking module, the viewing angle adjustment data using theone or more images.

Among other advantages, the disclosed technologies can maintain displayresolution while projecting different light fields simultaneously intovarious viewing directions. The disclosed technology can enable lightfield displays that do not require wearable devices such as glasses orheadsets for use. Disclosed display technologies can use temporal andspatial multiplexing for cheaper fabrication and more efficient use oflight emitting elements.

In some embodiments, the systems and methods described below may overlaycontent viewable within a narrow viewing angle on top of contentviewable within a wide viewing angle to supplement the wide viewingangle content, e.g., with menus or other content that some viewers donot need to see. For instance, the systems and methods described belowmay enhance presentation of content, e.g., a three-dimensional model, ina wide viewing angle by presenting less relevant content, e.g., a menu,in a narrow viewing angle. In some implementations, the systems andmethods described below may present sensitive content in a narrowviewing angle to increase security, privacy, or both, of the sensitivecontent while presenting non-sensitive content in a wide viewing angle,e.g., when the non-sensitive and sensitive content are related. In someimplementations, the systems and methods described below may useeye-tracking for a particular viewer to adjust the narrow viewing angleto follow movement of the particular viewer and reduce a likelihood thatother viewers can view the narrow viewing angle content.

The details of one or more embodiments of the subject matter of thisspecification are set forth in the accompanying drawings and thedescription below. Other features, aspects, and advantages of thesubject matter will become apparent from the description, the drawings,and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a light field display.

FIG. 2A is a plan view of an array of light field pixels from the lightfield display shown in FIG. 1.

FIG. 2B is a cross-sectional view of a light field pixel from the lightfield display shown in FIG. 1.

FIG. 2C is a cross-sectional view of a subpixel showing multipledirectional light emitters, including micro light emitting diodes(μLEDs).

FIG. 3A is a schematic cross-section of an embodiment of a micro-scaleresonant cavity LED.

FIG. 3B is a schematic cross-section of an embodiment of a μLED with aphotonic crystal.

FIG. 4 is a schematic cross-section of an array of μLEDs on a tiered (orterraced) substrate.

FIG. 5A is a schematic cross-section of a device including an array ofμLEDs optically coupled to a single light directing lens.

FIG. 5B is a schematic cross-section of a device including an array ofμLEDs optically coupled to a light directing mirror.

FIG. 6A is a schematic cross-section of a device including an array ofμLEDs optically coupled to a deformable lens.

FIG. 6B is a schematic cross-section of a device including an array ofμLEDs on a moving substrate optically coupled to a lens.

FIG. 6C is a schematic cross-section of a device including an array ofμLEDs optically coupled to a movable mirror.

FIG. 7A is a schematic diagram of a light field subpixel that uses acoherent light source.

FIG. 7B is a schematic diagram of another light field subpixel that usesa coherent light source.

FIGS. 8A-C show an example of an LED display with an array of pixelsubsets that present two overlaid images within a narrow viewing angleand present only one of the two images within a wide viewing angle.

FIG. 9 shows another example of a LED display with an array of pixelsubsets that presents two overlaid images of different sizes.

FIG. 10 is a flow diagram of a process for generating two overlaidimages using corresponding wide-angle and directional light emitters

FIG. 11 is a schematic diagram of a display including details of anelectronic controller.

FIG. 12 is a schematic diagram of an example computer system that can bepart of or used in conjunction with the devices described above.

Like reference numbers and designations in the various drawings indicatelike elements.

DETAILED DESCRIPTION

FIG. 1 is a schematic diagram of a light field display system 100. Thesystem includes a light field display 110 and a controller 120. Display110 includes an array of light field pixels 130, each configured to emitlight selectively into discrete angular directions within a viewingvolume of the display. Accordingly, light field display 110 displaysdifferent images to different viewing locations, as illustrated by afirst light field image 160 visible to a viewer located to a firstviewing location 140, and a second, different light field image 162simultaneously visible to a viewer at a second, different viewinglocation 150. A Cartesian coordinate system is shown for ease ofreference. In this reference frame, the z-axis is normal to the plane ofdisplay 110. The x-axis corresponds to the horizontal viewing directionand the y-axis to the vertical viewing direction.

Light field images are dynamically adjusted by controller 120, whichprovides coordinated control signals to each pixel 130, modulating eachpixel's corresponding light field.

During operation, controller 120 updates the light field images in eachdirection at a certain frequency (e.g., frame rate) that allows the eyeto perceive a continuous image. In general, the frame rate can vary. Insome embodiments, display 110 can deliver video light fields e.g., atframes rates of 30 Hz or more, 60 Hz or more, 120 Hz or more.

In general, display 110 can simultaneously project different images of asingle object or a sequence of images of the same scene (e.g., a movie)in multiple viewing directions. In some embodiments, e.g., where thelight field display has sufficient angular resolution, display 110 canprovide stereoscopic imagery to one or more viewers, providing a 3Dviewing experience. As illustrated, light field images 160 and 162 areimages of two different perspectives of a single object presented intoviewing locations 140 and 150 respectively. If these images of differentperspectives of a single object are displayed stereoscopically to theeyes of a single observer, that observer perceives a 3D image of thatobject. If a sequence of such images is displayed stereoscopically tothe eyes of a single observer, a 3D movie is perceived.

Alternatively, or additionally, light field display 110 can be used tosimultaneously present different images or different movies to viewerslocated in different viewing locations. For example, two viewers canwatch two different 2D movies on the same light field display or canwatch the same 3D movie but from two different perspectives.

In general, the size and resolution of display 110 can vary. Typically,display 110 has a diagonal dimension in a range from about 25 inches toabout 150 inches, although the disclosed technology can be applied tosmaller and larger displays. Resolution can be UXGA, QXGA, 480p, 1080p,4K UHD or higher, for example. Moreover, while display 110 is depictedas having a base mount, more generally the technology disclosed can beimplemented in other display form factors, such as, for example, wallmounted displays, billboard displays, mobile devices (e.g., handhelddevices, such as smartphones and tablet computers), wearable computers(e.g., smartwatches), etc.

Referring to FIGS. 2A and 2B, light field pixels 130 are arranged in anarray 200. Light field pixels 130 are each composed of three subpixels210 for three colors of the display: red (“R”), green (“G”), and blue(“B”). Full color images are spatially synthesized by proportionatecolor mixing of these three colors at different subpixel intensityoutputs in a particular direction. As shown in the cross-sectional view250 of pixel 130 in FIG. 2B, the three subpixels 210 are supported by asubstrate 230 (e.g., a semiconductor substrate).

Each subpixel 210 is, in turn, composed of an array of directional lightemitters 220, as shown in the inset in FIG. 2C. Directional lightemitters 220 emit light at wavelengths corresponding to the subpixelcolors R, G, or B in predominantly one direction.

By way of example, FIG. 2C is a schematic cross-section 260 of a bluesubpixel. Each directional emitter 220 includes a micro-light emittingdiode (μLED) 225 and a light directing element 262.

In combination, μLED 225 and light directing element 262, producedirectional light propagating predominantly along a single direction. Inother words, the emitted light has a principal direction 240 and issubstantially collimated. For example, each μLED 225 can be similarlyconfigured to emit substantially collimated light that is perpendicularto the x-y plane of the corresponding light directing element. Eachlight directing element 262 steers the light into a specific direction240 (e.g., the viewing direction). By using a different light directingelement for each μLED, each μLED in a subpixel directs light in uniquedirection.

In general, the degree of collimation of light emitted from directionallight emitter 220 can vary depending on the specific structure of theμLED and the light directing element. The degree of collimation can becharacterized by a divergence angle 242 at which intensity drops off tohalf of the intensity along the principle direction 240 (e.g., θ_(1/2)angle). As used herein, substantially collimated light is considered tobe weakly diverging light, having a divergence angle 242 of 15° or less(e.g., 10° or less, 8° or less, 5° or less, 3° or less, 2° or less, 1°or less). Substantially collimated light can include more highlycollimated light, such as light having a divergence angle 242 of 10° orless, 8° or less, 5° or less, 3° or less, 2° or less, 1° or less. Thisdivergence angle 242 corresponds to the solid angle of light 244 emittedfrom directional light emitter 220.

Light directing elements 262 for individual μLEDs 225 can be refractive(e.g., lenses, prisms) or diffractive (e.g., gratings, diffractivelenses, diffractive optical elements). Elements 262 can be deposited onμLED structures 225 using various microfabrication methods. For example,the elements can be deposited using sputtering, atomic layer deposition,or chemical vapor deposition. Photolithography techniques such asmasking and lift off can be used to selectively deposit differentdirecting elements 262 (e.g., directing light in different directions)on different μLED structures 225.

Although FIG. 2A shows a dense, square array 200 of pixels 130, otherarray geometries and densities are contemplated. Arrays can be 2D, asshown in FIG. 2A, or 1D, e.g., a line of pixels 130. Additionally, oralternatively, arrays can be sparse, with empty space between pixels130.

Although FIG. 2B shows adjacent color subpixels 210, other subpixelarrangements are contemplated. For example, subpixels 210 of differentcolors can be interleaved within pixel 130.

As noted above, light field display 110 has a resolution correspondingto the number of pixels in the display. This corresponds to theresolution of images produced by the display. In addition, light fielddisplay has an angular display resolution, which is determined by thenumber of μLEDs 225 in each subpixel, and corresponds to the number ofdiscrete viewing directions available to the display 110. In general,the angular resolution of display 110 therefore depends on both thenumber of individual light emitters in each subpixel and the divergenceangle of each emitter.

μLEDs are particularly suited to use in light field displays 110 becausethey can be made extremely small while still efficiently producingsufficient light for purposes of a display.

FIG. 3A shows an example μLED 225 that produces substantially collimatedlight: a micro-scale resonant cavity light emitting diode 300 (μRCLED).μRCLED 300 includes a diode layer 310 (e.g., light emitting diode, orLED) within an optical cavity defined by two reflector layers, 350 and360. μRCLED 300 emits light with a principal direction 240 perpendicularto diode layer 310.

As illustrated, diode layer 310 includes a hole transport layer 320, anelectron transport layer 330, and an active layer (or emission layer oractive region layer) 340. More generally, more complex diode structurescan be used, such as quantum heterostructures. The electron and holetransport layers are also known in the art as cladding or confinementlayers. The electron transport layer is in electrical contact withbottom contact electrode 355 through a via 366, and the hole transportlayer is in electrical contact with top contact electrode 365 through avia 367. Although FIG. 3A shows the hole transport layer above theelectron transport layer, the relative position of the electron and holetransport layers can be reversed without loss of function.

When a positive voltage is applied to electrode 365 with respect toelectrode 355 (e.g., when the diode layer is forward biased), electronscross from the electron transport layer 330 towards the hole transportlayer 320, recombining with holes in the active layer 340. Thisrecombination results in the isotropic emission of light of a wavelengthλ (e.g., electroluminescence). The wavelength(s) λ(s) of the emissiondepends on the bandgap of the transport 320/330 and active layer 340materials (e.g., semiconductors, or organic semiconductors). Fordisplays, the materials are chosen so that λ(s) are of visiblewavelengths of light (e.g., red light, green light, or blue light, orbetween 390 to 700 nm).

Bottom reflector 350 is highly reflective at λ(s) (e.g., thereflectance, R, is above 0.9 or 0.8 for the wavelength band ofoperation), while the top reflector 360 is partially transmissive toallow for emission of perpendicular light in principal direction 240(e.g., R is 0.9 or 0.8 or less and T is 0.01 or more). Alternatively, oradditionally, the top reflector can be designed with an aperture thatallows partial transmission of emitted light.

The top 360 and bottom 350 reflectors form a Fabry-Perot optical cavity.The cavity enhances spontaneous emission from active region layer 340 tothe modes of the cavity, resulting in higher spectral purity of theemitted wavelength λ. The cavity also makes the emission moreanisotropic (e.g., substantially collimated) by enhancing optical modesthat are perpendicular to the plane of diode layer 310 (e.g., light withprincipal direction 240). In other words, the cavity allows μRCLED 300to emit substantially collimated light in a principal direction 240 thatis perpendicular to the plane of the diode layer 310.

The thickness of the optical cavity in the z-direction can be designedto increase the spectral purity the emitted wavelength of the activeregion. The thickness of diode layer 310 defines the thickness (orlength) of the optical cavity (L). To limit the emission of active layer340 to a narrower spectral band around λ, the length of the opticalcavity can be an integer multiple of λ/2 so that L=N·λ/(2·n), where N isan integer between 1 and 10 and λ is the optical wavelength of thespontaneous emission of active layer 340 and n is the refractive indexof the diode layer. For example, for a red subpixel 210, where λ iscentered around 625 nm, and the refractive index is 2, the opticalcavity length (or thickness) can be between 150 nm and 1 μm. In general,the optical cavity length of μRCLED 300 for visible emissions can bebetween 100 nm and 10 μm. The resulting spectral bandwidth can have astandard deviation between 10 and 50 nm from λ.

One or both of reflectors 350 and 360 can be deposited reflective metallayers, Distributed Bragg Reflectors (DBRs), or other reflectivestructures. DBRs are formed from multiple layers of alternatingmaterials with varying refractive index, resulting in periodic variationin the effective refractive index in the structure. Each DBR layerboundary causes a partial reflection of an optical wave (e.g., ofemitted light). When the thickness of each layer is approximately equalto λ/4n, the many reflections of the emitted waves combine to result inconstructive interference, and the DBR layers act in combination as ahigh-quality reflector. The range of wavelengths that are reflected iscalled the photonic stopband. In other words, within this range ofwavelengths, light is “forbidden” from propagating in the structure.

For example, a multilayer DBR can be a quarterwave stack composed of aplurality of pairs (or periods) of semiconductor layers, with a numberof pairs ranging from 10 to 40. One semiconductor layer in each pair hasa higher index of refraction than the other semiconductor layer of thepair. The thickness of each semiconductor in the pair equals λ/4n,wherein λ is the optical spontaneous emission wavelength of the activeregion of the LED and n is the refractive index of the semiconductormaterial. For a device with an active region layer 340 spontaneouslyemitting at λ=0.87 μm, such as GaAs, a quarterwave stack of pairs ofsuch semiconductors as GaAs and AlAs with refractive indices of 3.64 and2.97, respectively, can consist of 62 nm thick GaAs layer and 73 nmthick AlAs layer while a stack of AlAs and Al_(0.05)Ga_(0.95)As canconsist of pairs of layers 73 nm and 60 nm thick each, respectively. Ina specific example, the DBR can be 30 pairs of n⁺-type (5×10¹⁷-5×10¹⁸cm⁻³) semiconductor layers forming the DBR mirror structure, each pairof the stack consisting of a 73 nm thick layer of n⁺-AlAs and 60 nmthick layer of Al_(0.14)Ga_(0.86)As.

In some embodiments, the materials of the DBR mirror can be selected toreduce losses such as the absorbance of the diode layer's 310electroluminescent emission by the DBR's multilayer mirror structure.

Semiconductor DBRs can be epitaxially grown from semiconductor substrate230 (e.g., using metal organic vapor phase epitaxy (MOVPE), metalorganic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE)or hydride vapor phase epitaxy (VPE)). For example, a semiconductor DBRcan be epitaxially grown on a highly doped semiconductor substrate 230that also provides as an ohmic contact for electrodes 355 or 365 (e.g.,as a contact layer). For example, substrate 230 can be a heavily dopedn⁺-type (or p-type) III-V or II-VI semiconductor, such as GaAs orAlGaAs. The thickness of the substrate can be from 100 μm to 500 μm andthe doping concentration of the substrate can range from 1×10¹⁷ to1×10¹⁹ cm⁻³. In some applications, the substrate can be first grown on amaster substrate of silicon, which is in common to a number of devicesgrown on the master substrate.

DBRs can also be formed from deposition of alternating layers using asatomic layer deposition, chemical vapor deposition (CVD), physical vapordeposition (PVD), ion beam sputtering, magnetron reactive sputtering,and plasma-ion-assisted deposition. For example, the top reflector inμRCLED 300 can be a DBR deposited on a previously fabricated diode layer310 via sputtering.

In some embodiments, the DBR is an air-gap DBR. Air-gap DBRs alternatelayers of air and a material, such as a semiconductor material. They canachieve higher reflectivity with fewer layers due to the higher contrastin refractive index. For example, such air gaps may be formed byselective wet or photochemical etching of sacrificial alternating layersin a semiconductor DBR. In some embodiments, the etching process can behalted before the entire sacrificial layer is removed, leaving behindsupport structures composed of the sacrificial layer material. In someembodiments, support posts are deposited between alternatingsemiconductor DBR layers using photolithography or other nanofabricationmethods.

In some embodiments, transport layers 320/330 and active layer 340 areIII-V or II-VI semiconductor materials, such as GaAs or AlGaAs.Additionally, or alternatively, the semiconductor materials can alsoinclude a single group four element (e.g., C, Si, Ge, Sn, etc.), or caninclude a compound with group 2 elements (Be, Mg, Ca, Sr, etc.), group 3elements (B, Al, Ga, In, etc.), group four elements, group 5 elements(N, P, As, Sb, etc.), group 6 elements (O, S, Se, Te, etc.) or any othersuitable composition. Example compounds include: AlGaInP, AlGaN,AlGaInN, Al(Galn)AsP, AlAs, GaAs, GaAsP, GaP, GaN, GaAlAs, InGaN, SiC,ZnO or the like.

With a semiconductor diode layer 310, the electron transport layer 330can be n-doped and the hole transport layer 320 can be p-doped. In someembodiments, the transport layers can be Al_(x)Ga_(1-x)As, where xranges from 0.1 to 0.4. For example, n-doped layer 330 can be n-typeAl_(0.30)Ga_(0.70)As and p-doped layer 320 can be p-typeAl_(0.30)Ga_(0.70)As. Active layer 340 may be lightly n- or p-doped(e.g., 1×10¹⁶-5×10¹⁷ cm⁻³ GaAs), or left undoped. Active layer 340 isselected to have a narrower bandgap than transport layers 320, 330. Forexample, the active layer can be a narrow bandgap semiconductormaterial, such as AlInGaP.

Transport layers 320/330 can each be between 0.1 μm and 8 μm thick(e.g., in z-direction in FIG. 3A). The total thickness of diode layer310 can be between 3 μm and 10 μm. In some embodiments, the totalthickness of diode layer 310 can be 10 μm or less, 5 μm or less, or 3 μmor less. The thickness can be tuned to define a desired optical cavitylength, as detailed above. In a specific example, diode layer 310includes an electron transport layer 330 of n⁺-Al_(0.20)Ga_(0.80)As(5×10¹⁷ cm⁻³) about 140 nm thick, a lightly doped (5×10¹⁶ cm⁻³) activelayer 340 of p⁻-GaAs about 10 nm thick, and a hole transport layer 320of p⁺-Al_(0.30)Ga_(0.70)As (5×10¹⁶ cm⁻³) about 80 nm thick.

As noted previously, mLEDs are extremely small. The lateral dimension ofdiode layer 310 (e.g., in x-direction in FIG. 3A) is generally 100 μm orless, and can be 50 μm or less, 20 μm or less, 10 μm or less. Smalllateral dimensions means that a number of μLEDs 225 can be used in asingle subpixel 210, while maintaining an overall low pixel size andhigh resolution.

However, without being bound to theory, such small lateral dimensionscan also lead to appreciable decreases in quantum efficiency in activelayer 340 due to surface charge trapping and recombination. Chargetrapping and recombination may be the product of undesired interfacialchemical groups such as O—H groups, dangling bonds, etc., and may resultin usable energy being converted into heat. This is particularlyapparent in micro-scale devices—especially red emitting micro-scaledevices—where charge carrier diffusion lengths approach the lateraldimensions of the device. U.S. application Ser. No. 15/005,872, entitledHigh-Efficiency Light Emitting Diode, and incorporated in its entiretyherein by reference, discloses diode layer 310 design modifications thatcan reduce surface charge trapping and recombination by preventingelectrons/holes in active layer 340 from reaching the surface of thesemiconductor material.

All semiconductor layers in diode layer 310, just likesemiconductor-based DBRs 350 and/or 360, can be epitaxially grown from asemiconductor substrate 230 (e.g., using MOVPE, MOCVD, MBE, or VPE). Insome embodiments, the bottom DBR, diode layer, and optionally the topDBR can be grown on a sacrificial epitaxial substrate. The substrate canbe subsequently etched, and the DBR-diode-DBR or DBR-diode stacks can bereleased from the substrate. Such stacks can be released into solutionor mechanically detached with a resin stamp. The stacks can then bearrayed on a non-native substrate using chemical patterning ormechanical deposition techniques (e.g., stamping). With the use ofsacrificial epitaxy and arrangement of diode stacks on a non-nativesubstrate, stacks with different emissive bandwidths (e.g., thosecorresponding to R/G/B subpixels) can be placed adjacently in a singlearray, for example, an array making up all subpixels 210 of pixel 130.In the case of DBR-diode stacks arrayed on a non-native substrate, topreflector 360 (e.g., a second DBR) can be deposited on top of diodelayers 310 of the stacks using sputtering with photolithographypatterning and liftoff techniques.

The contact electrodes 355, 365 can be formed from any material that issufficiently conductive to produce an ohmic contact with the transportlayers. For example, the electrode can be a metal, such as Indium, Ag,Al, Ni, Ti, Au—Zn and Au—Be. The electrodes can be formed by knownmicrofabrication methods, including lithographic patterning, deposition,and etching techniques. The electrodes can be 1 μm to 10 μm inthickness.

Electrodes 355, 365 can be designed so as to not interfere with theoptical and emissive properties of μRCLED 300. For example, in someembodiments, especially when reflector layer 350/360 is not itselfconductive, electrodes 355, 365 can be applied to a small,non-centralized area of the diode layer and can make contact with thetransport layer(s) 320/330 using vias 366 formed through the reflectorlayer(s), as shown in FIG. 3A. Alternatively, or additionally, anon-central part of the reflector layer(s) can be removed (e.g., usingphotolithography and/or selective etching techniques) and replaced withan electrode material.

If reflector layer 350/360 is itself conductive, then electrodes 355/365can make direct contact with reflector layer 350/360, instead of diodelayer 310. In some embodiments, conductive reflector layer 350/360 canalso itself act as an electrode.

In some embodiments, the top electrode 365 is reflective. If electrode365 is reflective, it can be used instead of the top 360 and/or bottom350 reflector layers to form the optical cavity.

In some embodiments, top electrode 365 is transmissive to emittedwavelength λ. In some embodiments, this transmissive electrode 365 canbe applied to the entire planar dimension of top reflector 360 withoutaffecting the optical properties of μRCLED 300.

In some embodiments, a highly doped contact layer is provided betweencontact electrodes 355/365 and the transport layers 320/330 to establisha non-alloyed ohmic contact. For example, the contact layer can be ann+-type or p type III-V or II-VI semiconductor, such as GaAs or AlGaAs.The thickness the contact layer can range between 3 nm to 50 nm and thedoping of the contact layer can be between 1×10¹⁷ to 1×10²⁰ cm⁻³. Insome embodiments, the contact layers can cover the entire top (orbottom) transport layer without interfering with the optical propertiesof μRCLED 300. In some embodiments, the top 360 and/or bottom 350reflector are sufficiently electrically conductive to act as contactlayers.

Although the above embodiments were described in terms of semiconductortransport 320/330, contact, and active 340 layers, one or more of thoselayers can be substituted with an organic electronic material. Organicelectronic materials include conductive polymers such as polyacetylene,polypyrrole, polyaniline, and their copolymers. Poly(p-phenylenevinylene) and its derivatives, and polyfluorene, can be used aselectroluminescent semiconducting polymers.

An OLED (organic light-emitting diode) is composed of a thin film oforganic material (e.g., active layer 340) that emits light understimulation by an electric current. An OLED can include an anode (e.g.,electron transport layer 330), a cathode (e.g., hole transport layer320), an OLED organic material (e.g., active layer 340), and aconductive layer.

OLED organic materials can be categorized into two major families:small-molecule-based and polymer-based. Small molecule OLEDs (SM-OLEDs)include organometallic chelates(Alq3), fluorescent and phosphorescentdyes, and conjugated dendrimers. Fluorescent dyes can be selectedaccording to the desired range of emission wavelengths; compounds likeperylene and rubrene can be used. Devices based on small molecules canbe fabricated by thermal evaporation under vacuum. While this methodenables the formation of well-controlled homogeneous film, it can belimited by high cost and limited scalability.

Polymer light-emitting diodes (PLEDs), similar to SM-OLED, emit lightunder an applied electric current. Polymer-based OLEDs can be moreefficient than SM-OLEDs requiring a comparatively lower amount of energyto produce the same luminescence. Common polymers used in PLEDs includederivatives of poly(p-phenylene vinylene) and polyfluorene. The emittedcolor can be tuned by substitution of different side chains onto thepolymer backbone or modifying the stability of the polymer.Polymer-based OLEDs can be processed using solution-based techniques.Compared to thermal evaporation, solution based methods can be moresuited to creating films with large dimensions.

Although the prior discussion focused on μRCLEDs as emitters, otherμLEDs 225 that can provide substantially collimated light arecontemplated. For example, FIG. 3B shows a different example of such aμLED structure: a photonic crystal μLED 370. Instead of using reflectorsto form an optical cavity as shown in FIG. 3A, diode layer 310 ispositioned adjacent to a 2D photonic crystal 380 in μLED structure 370.The dimensions and material considerations are otherwise similar toμRCLEDs 300. Electrodes 355 and 365 still provide forward bias tostimulate emission in active layer 340 of diode layer 310. Instead ofenhancing perpendicular optical modes (as in a μRCLED 300 cavity), thecrystal in μLED structure 370 can be designed to suppress optical modesin the plane of the diode layer. Thus, both μLED structures 300 and 370generate light of wavelength λ emitted in a principal perpendiculardirection 240 from active layer 340.

Photonic crystals, such as crystal 280, are composed of periodicdielectric, metallo-dielectric—or even superconductor microstructures ornanostructures—that affect electromagnetic wave propagation in a similarway to how a periodic potential in a semiconductor crystal affectselectron motion by defining allowed and forbidden electronic energybands. Photonic crystals contain regularly repeating regions of high andlow dielectric constant. Photons (behaving as waves) either propagatethrough this structure or not, depending on their wavelength.Wavevectors that propagate are called modes, and groups of allowed modesform bands. Disallowed bands of wavelengths are called photonic bandgaps.

Photonic crystals can be fabricated for one, two, or three dimensions.One-dimensional photonic crystals, such as DBRs discussed above, can bemade of layers deposited or stuck together. Two-dimensional crystals canbe made by photolithography, or by drilling periodically-spaced holes ina suitable substrate. Holes may be drilled in a substrate that istransparent to the wavelength of radiation that the bandgap is designedto block. Triangular and square lattices of holes can be employed.

For photonic crystal μLED 370, the photonic bandgap can be chosenexclude the emission wavelength λ of the active region in order to allowfor the transmission of such light through the top of the μLED structure370. The bandgap can include modes of emitted light which are notperpendicular to diode layer 310. Specifically, the resulting emittedlight has a principal direction 240 perpendicular to diode layer 310 andis substantially collimated to an angular distribution of θ_(1/2) of 15°or less, as discussed previously.

FIGS. 3A-3B provide two examples of μLEDs 225 that can producesubstantially collimated light emitted in a perpendicular principaldirection 240 from an organic or inorganic diode layer 310. As noted inreference to FIG. 2C, light from each μLED 225 can be directed intospecific directions by light directing elements 262. Other techniquesfor directing substantially collimated light from emitters are alsocontemplated, however.

For example, in some embodiments, the substrate of a μLED 225 array canbe structured to provide control of directionality. As shown in FIG. 4,an array 400 includes μLEDs 225 (individually 401(A)-(D)) on structuredsubstrate 402. μLEDs 401(A)-(D) emit light in respective principaldirections 440(A)-(D), each direction substantially perpendicular to thelayers forming the μLED, as discussed above. However, the surface ofsubstrate 402 that supports μLEDs 225 is not a planar surface, butincludes inclined portions 410(A) and 410(C) along with portions 410(B)and 410(D) that lie parallel to the x-y plane. Inclined portions 410(A)and 410(C) can be formed by terraces 404, as shown in the inset in FIG.4. As shown, the terraces are much smaller than the size of the μLEDs,so that the terraced surface presents an effectively flat surface onwhich the μLEDs are placed. The principle direction of each respectiveμLED is tilted by an angle corresponding to the wedge angle of eachinclined portion 410(A) and 410(C). Accordingly, the strategic placementof μLEDs 225 on differently inclined portions results in light beingoriented into different viewing directions 440(A)-(D).

Substrate terracing can be formed, for example, by selective chemicaletching of substrate 402 (e.g., a semiconductor substrate). μLEDs401(A)-(D) can be arrayed on the substrate via soft lithography transfermethods, such as stamping. Such methods can allow for adjacent placementof elements 401 that emit light at different wavelengths, for example aselements in adjacent subpixels 210.

In some embodiments, a single light directing element can be used todirect light emitted from a number of light emitting elements into acorresponding one of a number of different directions. Advantageously,using a single light directing element for multiple emitters can thedecrease the overall number of light directing elements, lowering costs,simplifying synthesis, and/or reducing design constraints.

For example, FIG. 5A shows a device 500 with a number of μLED structures225 on substrate 514. A single refractive light directing element 502(e.g., a lens) directs the light emitted from the μLEDs 501(A)-(D) intodifferent respective principal directions 540(A)-(D). Alternatively, oradditionally, a single diffractive light directing element (e.g., adiffractive lens or holographic optical element) can be used to directthe light emitted from a number of μLEDs into different directions.

While the foregoing examples have all featured light emitters that emitlight towards the viewing side of the display (e.g., using transmissivelight directing element(s) to steer the light), other arrangements arealso possible. For example, light field pixels can utilize emitters thatface towards the back of the display and use one or more reflectivelight directing elements to reflect emitted light towards the viewingside. Referring to FIG. 5B, a device 510 includes μLEDs 501(A)-(D) withrespective refractive light directing elements 262 on transmissivesubstrate 516. Light emitted from μLEDs 501(A)-(D) is directed intodifferent respective principal directions 540(A)-(D) by light directingelements 262, and is reflected form a single reflective light directingelement 512 (e.g., a mirror). The light reflecting element 512 allowslight from a number of directing elements to be re-directed and emittedthrough transparent substrate 516 towards the viewer(s).

As noted previously, light field display 110 can achieve a high displayresolution and a high angular resolution by taking advantage of thesmall lateral dimension of each μLED structure 225 (e.g., under 100 μm).A high angular resolution is achieved because many such small μLEDs 225can fit into a single subpixel 210 in display 110 (e.g., in 1D or 2Darrays). However, while the foregoing embodiments feature a single lightemitter for each discrete light emission direction in a light fielddisplay subpixel, temporal multiplexing techniques can also be used toincrease the angular resolution of each subpixel or simplify thestructure of a light field subpixel by using fewer light emitters toachieve a desired angular resolution. Temporal multiplexing involvesusing a single light emitter to sequentially direct light into more thanone angular range during each image frame.

Due to the switching speed and high brightness of the μLEDs, each cangenerate sufficient optical power in a fraction of the duty cycle foreach frame. Thus, each μLED can be used to direct light into multipledirections for each frame. As a consequence, temporal multiplexingallows display 110 to use a fraction of the μLEDs it would otherwiseneed to generate the same angular display resolution.

In addition to decreasing the number of μLED structures 225 required formaintaining angular resolution, a multiplexed display can have severalother advantages compared to a non-multiplexed display. They can requirefewer wires or electrical connections and simpler driving electronics.They can also lead to reduced cost and/or reduced power consumption.

FIGS. 6A-6C show different embodiments of light field pixel structurescapable of temporal multiplexing in light field display 110. Referringto FIG. 6A, device 600 includes μLEDs 601(A)-(D) arrayed on a substrate514. Due to the varying local curvature of its exit surface 605, lens602 directs light emitted from μLED 601(A)-(D) into respective principaldirections 640(A)-(D).

Actuator 604 causes the curvature of the exit surface 605 of lens 602 tochange to a different curvature, e.g., 606. This change in curvatureresults in a different local incident angle of emitted light at the exitsurface and a corresponding change in the refraction of light emittedfrom μLEDs 601(A)-(D), from initial respective principal directions640(A)-(D) into modified principal directions 641(A)-(D). Thus,deformation of lens 602 can be used to temporally multiplex the display,using controller 120, and allow each light emitting element to directlight into multiple directions (e.g., 640(A) and 641(A)) in a singledisplay frame.

Lens 602 has material properties that allow for predictable, reversible,and fast deformation appropriate for multiplexing (e.g., greater than30-60 frames per second). Such directing elements 602 can bemechanically or electrically tunable. For example, an electroactiveelastomer-liquid lens system or dielectric elastomer actuators can beused.

Additionally, or alternatively, the optical properties (e.g., refractiveindex) of a light directing element can be changed without physicaldeformation (e.g., using electro-optic effects). For example, liquidcrystals can provide controlled refractive index changes withoutmechanical movement upon application of electric signals. Such changescan be used for temporal multiplexing, and can avoid mechanical straincaused by repetitive deformation of the material.

While device 600 achieves temporal multiplexing by actuating the lightdirecting element, other adjustment schemes are also possible. Forexample, alternatively, or additionally, the light emitters can be movedrelative to the light directing element during each frame. Referring toFIG. 6B, a device 610 includes μLEDs 601(A)-(D) arrayed on a substrate514. Lens 502 (or some other light directing element) directs lightemitted from μLEDs 601(A)-(D) into respective principal directions μLEDs640(A)-(D).

Temporal multiplexing is achieved by using actuator 614 to movesubstrate 514 with respect to the light directing element 502. Thismovement results in a different local incident angle of emitted light atthe exit surface 615 of lens 502 and a corresponding change in therefraction of light emitted from μLEDs 601(A)-(D), from initialrespective principal directions 640(A)-(D) into modified principaldirections 641(A)-(D).

Additionally, or alternatively, relative movement between the lightdirecting element and the light emitting element array can be achievedin various ways. For example, substrate 514 can be placed on apiezo-electric stage and the relative movement can be electricallycontrolled.

Temporal multiplexing can also be achieved using a MEMS mirror. Forexample, referring to FIG. 6C, a device 620 includes μLEDs 601(A)-(D)with respective refractive light directing elements 262 arrayed on atransmissive substrate 516. Light emitted from μLEDs 601(A)-(D) isdirected into different principal directions (640(A)-(D) respectively)by the light directing elements 262, and is reflected form a singlereflective light directing element 512 (e.g., a mirror). The lightreflecting element 512 allows light from a number of directing elementsto be re-directed through transparent substrate 516.

In order to achieve temporal multiplexing, actuator 624 controls thetilt of light reflecting element 512, from initial position 630(A) to adifferent position, e.g. 630(B), changing the principal direction oflight emitted from μLEDs 601(A)-(D), e.g., to μLEDs 641(A)-(D)respectively. Any electrically-tunable actuation mechanism can be usedfor actuator 624. For example, microelectromechanical systems (MEMs) canbe used. MEMs devices use miniaturized mechanical and electro-mechanicalelements (e.g., devices and structures) made using the techniques ofmicrofabrication.

Additionally, or alternatively, the individual refractive lightdirecting elements 262 can be eliminated from device 620, and the singlemirror 512 replaced with a micro-mirror spatial light modulator (SLM).Each micro-mirror of the SLM can be used to change the direction oflight emitted from a single μLED. An example of such an SLM system isthe Digital Micromirror Device (DMD): a semiconductor-based light switcharray of thousands of individually addressable, tiltable, mirror-pixels.

Although the above embodiments are shown as using μLED structures 225,any light emitting elements of similar dimensions that can producesubstantially collimated light can be used in light field displays 110disclosed herein. For temporal multiplexed displays, light emittingelements with similar intensity and switching speeds to the describedμLED structures 225 can be used.

The light field display subpixels described above generally involve theuse of incoherent light. However, more generally, light field pixelsthat use coherent light sources also can be used. For example, usingcoherent light, a light field subpixel can variably spatially-modulate aphase of a wavefront emitted from the pixel so that, in the far field,the light intensity from the subpixel varies as a function of viewingangle. Collectively, the subpixels operate to display a light fieldimage as the described in the embodiments presented above.

An example of an apparatus 700 including such a light field subpixel isshown in FIG. 7A. Here, a light field subpixel 720 receives coherentlight (e.g., polarized coherent light) from a light source 710 via awaveguide 712 (e.g., a fiber waveguide) and an input coupler 714.

Subpixel 720 includes multiple (in this case, eight) phase-shiftingelements 722, which are arranged to receive light from input coupler 714via waveguides. Each phase-shifting element 722 introduces a variablephase shift to the coherent light it receives from input coupler 714 andto output light to a corresponding output coupler 724, which emits thephase-shifted light from subpixel 720. Subpixel 720 also includes alight-splitter 726 that facilitates distribution of light from inputcoupler 714 to some of the phase-shifting elements.

Light field subpixel 720 emits in the near field, via output couplers714, a collection of coherent wavefronts (illustrated by rays 740) whichare phase-shifted relative to each other by the phase shift introducedby phase shifting elements 722. In the far field, interference betweenthe wavefronts results in a varying intensity of the subpixel dependingon which viewing angle the pixel is viewed from (illustrated by rays742).

In general, any suitably compact variable phase shift element can beused. For example, phase shifting elements 722 can be composed of anelectro-optic waveguide modulator, which can vary the optical pathlength of the light in the waveguide, by application of an electricfield across the waveguide. Non-linear optical crystals (e.g., lithiumniobate) or nonlinear optical organic polymers can be used in suchmodulators. Additionally or alternatively, phase shifting elements 722can use thermo-optic effects (e.g., refractive index change withtemperature). Similarly, any suitable outcoupling element can be used,such as a grating, photonic crystal, a mirror, or a lens.

In some implementations, light source 710 supplies light to multiplesubpixels. Generally, at least one light source for each subpixel coloris used.

FIG. 7B shows another example of a light field subpixel 750 that usescoherent light source 710. Here, subpixel 750 includes a spatial phasemodulator 760. Like apparatus 700, subpixel 750 receives coherent light(e.g., coherent polarized light) from light source 710 via a waveguide712 and input coupler 714. Subpixel 750 further includes a beam shaper752 and collimator 754 which function to spread and collimate light frominput coupler 714 to provide a planar wavefront that fills the apertureof spatial phase modulator 760.

Spatial phase modulator 760 includes a spatial array of variable phasedelay elements 762 which, collectively, introduce variable phase delayacross an incident wavefront so that the wavefront emitted (770) fromthe subpixel takes on the desired far field intensity pattern (772).Spatial phase modulator 760 is analogous to a switchable phase gratingor switchable hologram, in which the emitted wavefront is diffracted ina manner that results in the desired far field light intensity pattern.Although depicted as a one dimensional array, two dimensional arrays ofphase delay elements 762 are also possible.

Spatial phase modulator 760 can utilize a variety of electro-optictechnologies for introducing a variable phase shift to a wavefrontincident across the modulator. For example, a liquid crystal device canbe used. For instance, spatial phase modulator 760 can include a layerof a liquid crystal material between transparent electrode layers,patterned to allow for the orientation of LC molecules in the layer tobe separately controlled at each element by application of a suitablevoltage across each element. For polarized light traversing the LClayer, the phase of the light exiting modulator 760 will depend on theamount of retardation experienced in the LC layer, which in turn dependson the LC molecules orientation. Other electro-optic materials, such ascrystals which exhibit the Pockels effect or Kerr effect, can also beused. For example, spatial light modulator 760 can include such aslithium niobate or gallium arsenide and in other noncentrosymmetricmedia such as electric-field poled polymers or glasses.

Light field subpixels 720 and 750 can be formed using integrated optics,free-space optics, fiber optics, alone or in combination. For example,light field subpixel 720 can be formed using integrated optics (e.g.,the subpixel can be integrated in a monolithic substrate usingfabrication techniques common to wafer processing) but coupled to lightsource 710 using fiber optics. Light field subpixel 750 can be formedusing a combination of free space optics (e.g., beam shaper 752 andcollimator 754) and integrated optics (e.g., spatial phase modulator760), and coupled to light source 710 using fiber optics.

While the directional emitters disclosed above are described in relationto a light field display, they can be advantageously incorporated inother types of displays. For example, they can be used in displays thatare capable of overlaying specific information that is viewable onlyfrom certain positions with a displayed image that is observable to allviewers. For instance, FIGS. 8A-C show an example of a light emittingdiode (LED) display 800 with an array of pixel subsets 802 that presenttwo overlaid images within a narrow viewing angle and present only oneof the two images within a wide viewing angle. For instance, the LEDdisplay 800 may present a first image that includes wide viewing anglecontent 810-12 and a second image that includes narrow viewing anglecontent 806-08. The LED display 800 presents the second image overlaidon top of the first image, as an overlaid image 804 a, which is viewablewithin a narrow viewing angle. The LED display 800 presents only thefirst image 804 b that is viewable within a wide viewing angle 814 thatis greater than the narrow viewing angle.

The second image may include content that viewable by one or only a fewviewers. For instance, the second image may include sensitive content,content that may detract from presentation of the first image 804 b, orboth.

In FIGS. 8A-B, the second image includes a menu with an object typeselector 806 and an object color selector 808. The first image 804 bincludes an office building 810 and a government building 812. Forexample, the first image 804 b may depict an architectural design of aplanned development and the second image may depict a menu of options tocustomize the buildings presented in the first image 804 b.

The object type selector 806 may allow selection of buildings ofdifferent types. The selection may cause a change in type of a buildingcurrently presented in the first image 804 b, or selection of a type forbuilding that can be added to the presentation of the first image 804 b.The object color selector 808 may allow selection of a color for aselected building presented in the wide viewing angle content 804 b.

Presentation of the overlaid image 804 a, that includes the first imageand the second image, allows one or only a few viewers to view thenarrow viewing angle content 806-08 concurrently while viewing the wideviewing angle content 810-12. For instance, the LED display 800 maypresent the overlaid image 804 a to one or more speakers who are givinga presentation. The speakers may use the menu, depicted in the secondimage from the overlaid image 804 a, to control the presentation, e.g.,by changing the content shown in the first image.

The LED display 800 allows additional viewers, e.g., other than thespeakers, to view the first image 804 b depicting the wide viewing anglecontent 810-12 within a second viewing angle 814 that is greater thanthe viewing angle for the narrow viewing angle content 806-08. At leastsome of the additional viewers, and potentially all of the additionalviewers, are unable to see the narrow viewing angle content 806-08because they are located outside of an area defined by the narrowviewing angle. For example, the additional viewers may view the firstimage 804 b from any position within a conference room that includes theLED display 800 while only the speakers, at the front left side of theconference room, can see the overlaid image 804 a that includes thenarrow viewing angle content 806-08. In some examples, the menu mayallow the speakers to navigate through a presentation, e.g., a slidepresentation, without showing the menu to the additional viewerswatching the presentation.

To cause presentation of the first image separately from the secondimage, and for both images to have different viewing angles, the LEDdisplay 800 includes the array of pixel subsets 802. The array of pixelsubsets 802 includes both wide-angle light emitters that present thefirst image at the wide viewing angle 814 and directional light emittersthat present the second image at the narrow viewing angle, e.g.,including and around presentation of the overlaid image 804 a. In someexamples, the narrow viewing angle may be limited to a region defined bythe overlaid image 804 a.

As shown in FIG. 8C, pixel subsets 802 a in the array of pixel subsets802 may include color specific pixel sub-subsets 816 a-c. Each of thecolor specific pixel sub-subsets 816 a-c, included in the pixel subset802 a, includes at least one directional light emitter for therespective color and at least one wide-angle light emitter for therespective color. The color specific pixel sub-subsets 816 a-c may bered, green, and blue. In some examples, a pixel subset 802 a may includefour or more color specific pixel sub-subsets 816, e.g., cyan, magenta,yellow, and black.

When the color specific pixel sub-subset 816 a is red, the colorspecific pixel sub-subset 116 a includes a red directional light emitterand a red wide-angle light emitter. Similarly, when the color specificsub-subset 816 b is blue, that sub-subset includes a blue directionallight emitter and a blue wide-angle light emitter. A green colorspecific sub-subset 816 c includes a green directional light emitter anda green wide-angle light emitter.

In some examples, a light emitter of one angle type is adjacent to alight emitter of another different angle type, e.g., without anyintervening light emitters between the two. For instance, the reddirectional light emitter may be adjacent to the red wide-angle lightemitter without any intervening light emitters, e.g., when both lightemitters are in the same color specific sub-subset 816 a-c.

In some implementations, pixel subsets 802 b in the array of pixelsubsets may include viewing angle specific sub-subsets 818 a-b. Forinstance, a pixel subset 802 b may include a directional pixelsub-subset 818 a and a wide-angle pixel sub-subset 818 b. Thedirectional pixel sub-subset 818 a includes a directional light emitterfor each color from a group of multiple colors. For instance, thedirectional pixel sub-subset 818 a may include a red directional lightemitter, a blue directional light emitter, and a green directional lightemitter. In some examples, the directional pixel sub-subset 818 a mayinclude a cyan directional light emitter, a magenta directional lightemitter, a yellow directional light emitter, and a black directionallight emitter.

The wide-angle pixel sub-subset 818 b includes a wide-angle lightemitter for each color in the group of multiple colors. For instance,the wide-angle pixel sub-subset 818 b may include a red wide-angle lightemitter, a blue wide-angle light emitter, and a green wide-angle lightemitter. In some examples, the wide-angle pixel sub-subset 818 b mayinclude a cyan wide-angle light emitter, a magenta wide-angle lightemitter, a yellow wide-angle light emitter, and a black wide-angle lightemitter.

When the LED display 800 includes angle specific sub-subsets 818 a-b,each of the sub-subsets may include light emitters of a particular angletype that are adjacent to each other. For instance, a directional pixelsub-subset 818 a includes three or more directional light emitters, eachof which are adjacent to two or more of the other directional lightemitters in the directional pixel sub-subset 818 a. A wide-angle pixelsub-subset 818 b may include three or more wide-angle light emitters,each of which are adjacent to two or more of the other wide-angle lightemitters in the wide-angle pixel sub-subset 818 b.

At least some of the light emitters of a particular angle type may beadjacent to both light emitters of the same angle type and lightemitters of the other angle type. For example, one of the directionallight emitters in the directional pixel sub-subset 818 a, such as theblue directional light emitter, may be adjacent to the other directionallight emitters in the directional pixel sub-subset 818 a, such as thegreen and the red directional light emitters, and at least onewide-angle light emitter in the wide-angle pixel sub-subset 818 b, suchas the green and red wide-angle light emitters.

In some implementations, the array of pixel subsets 802, shown in FIGS.8A-B, may include two sub-arrays of pixels. A first sub-array mayinclude the wide-angle pixel subsets. A second sub-array may include thedirectional pixel subsets. For instance, the first sub-array and thesecond sub-array may be interwoven such that wide-angle light emittersin the first sub-array are near or adjacent to corresponding directionallight emitters in the second sub-array.

When the LED display 800 includes two sub-arrays, each of the sub-arraysmay have the same number of pixel subsets. For instance, the LED display800 may have emitters of one angle type that correspond to an emitter ofthe other angle type. A wide-angle light emitter in a first sub-arraymay correspond to a directional light emitter in a second sub-array whenthe two light emitters have the same coordinates in images generated bythe corresponding sub-arrays. For instance, a particular wide-anglelight emitter, or group of wide-angle light emitters, e.g., withdifferent colors, may generate a particular x-y pixel in a first image.A particular directional light emitter, or group of directional lightemitters, e.g., with different colors, that correspond to the particularwide-angle light emitter may generate a particular x-y pixel in a secondimage, such that both of the particular x-y pixels have the samecoordinates in their respective image.

FIG. 9 shows another example of a LED display 900 with an array of pixelsubsets 902 that presents two overlaid images of different sizes. Thetwo images may have the same resolution, e.g., and a different quantityof pixels per inch, or different resolutions.

The LED display 900 may generate a first wide-angle image 904 that isviewable within a first wide viewing angle. The LED display 900 maygenerate a second directional image 906 concurrently with the firstwide-angle image 904. The second directional image 906 has a narrowviewing angle that is smaller than, included within, or both, the firstwide viewing angle.

The second directional image 906 may include supplemental content, suchas a menu, for the first wide-angle image 904. For instance, the seconddirectional image 906 may include menu options to allow a viewer tochange content, or the appearance of content depicted, in the firstwide-angle image 904.

The LED display 900 may include, as the pixel subsets 902, one or bothof the pixel subsets 802 a-b described with reference to FIG. 8C. Any ofthe features described with reference to the LED display 800 or the LEDdisplay 900 may be used with the other LED display unless otherwiseindicated. For example, the pixel subsets 902 may be color specific, orviewing angle specific, as described in more detail above.

In some examples, the LED display 900 may include an array of pixelsubsets 902 that include light emitters of only one angle type, e.g.,wide-angle or directional. For example, the LED display 900 may includea first pixel sub-array that includes only wide-angle pixel subsetswhich are used to generate the first wide-angle image 904 and a secondpixel sub-array that includes only directional pixel subsets which areused to generate the second directional image 906.

The LED display 900 may include a sub-array that includes light emittersof both angle types. For example, when the first wide-angle image 904has a different resolution or a different quantity of pixels per inch,or both, from the second directional image 906, the LED display 900 mayinclude a first sub-array of wide-angle light emitters that generate theportion of the first wide-angle image 904 upon which the seconddirectional image 906 is overlaid and that are near, e.g., within athreshold distance from, corresponding directional light emitters thatgenerate the second directional image 906. A second sub-array mayinclude the wide-angle light emitters that generate the portion of thefirst wide-angle image 904 upon which the second directional image 906is not overlaid, that are not within a threshold distance from acorresponding directional light emitter, or both. In this example, thedirectional light emitters may be located within a center of the LEDdisplay 900 and not located adjacent to at least one outside edge of theLED display 900, e.g., not located adjacent to any of the outside edgesof the LED display 900.

FIG. 10 is a flow diagram of a process 1000 for generating two overlaidimages using corresponding wide-angle and directional light emitters.For example, the process 1000 can be used by the LED display 800 shownin FIGS. 8A-B or by the LED display 900 shown in FIG. 9.

An LED display generates, using a plurality of wide-angle emitters, afirst display image viewable in a first viewing angle (1002). Forinstance, the LED display may use a first array of wide-angle emittersto generate the first display image of content that is viewable bymultiple viewers at multiple different viewing angles within the firstviewing angle.

The LED display generates, using a plurality of directional emittersconcurrently with generation of the first display image, a seconddisplay image that includes a different image than the first displayimage and is viewable in a second viewing angle (1004). For example, theLED display uses a second array of directional light emitters, that areseparate from the wide-angle light emitters, to generate the seconddisplay image that is viewable within the second viewing angle that maybe narrower than the first viewing angle.

The concurrent presentation of the first display image and the seconddisplay image may include an initial presentation of one image after theother image or an initial presentation of both images at substantiallythe same time. For instance, the LED display may concurrently generatethe first display image and the second display image at substantiallythe same time using the respective emitters. In some examples, the LEDdisplay may initially generate the second display image using thedirectional emitters and then generate the first display image using thewide-angle emitters such that the second display image is presented fora period of time before the first display image is presentedconcurrently with the second display image. The LED display mayinitially generate the first display image using the wide-angle emittersand then generate the second display image using the directionalemitters such that the first display image is presented for a period oftime before the second display image is presented concurrently with thefirst display image.

In some examples, each of the directional light emitters is adjacent toa wide-angle light emitter. A directional light emitter of a particularcolor, e.g., each directional light emitter, may be adjacent to awide-angle light emitter of the particular color. Each of the wide-anglelight emitters may be adjacent to a directional light emitter, e.g., ofthe same color.

In some implementations, each of the light emitters is adjacent to lightemitters of different colors than a color of the respective lightemitter. For instance, each red directional light emitter may beadjacent to a green directional light emitter and a blue directionallight emitter. Each of the wide-angle light emitters may be adjacent towide-angle light emitters of different colors than a color of therespective wide-angle light emitter.

The LED display determines whether viewing angle adjustment data hasbeen received (1006). The LED display may use any appropriate method todetermine whether viewing angle adjustment data, e.g., for thedirectional light emitters, has been received.

For instance, when the LED display includes a camera, the LED displaymay use an eye-tracking component to determine eye movement data for aviewer using multiple images of the viewer that were captured by thecamera. The eye-tracking component may use the eye movement data togenerate viewing angle adjustment data that indicates a change to theviewing angle of one or more of the directional light emitters. Theviewing angle adjustment data may identify different adjustments foreach of the directional light emitters, adjustments that apply to groupsof two or more directional light emitters, or a single adjustment thatapplies to all of the directional light emitters. The eye-trackingcomponent may provide the viewing angle adjustment data to an electroniccontroller to cause the electronic controller to adjust the secondviewing angle.

In some implementations, the LED display may include a communicationmodule that receives the viewing angle adjustment data. For example, thecommunication module may communicate with another system or device, suchas a laptop computer, that includes a camera and an eye-trackingcomponent that generates the viewing angle adjustment data. Thecommunication module may receive the viewing angle adjustment data overa wired connection, a wireless connection, or both. The communicationmodule may provide the viewing angle adjustment data to an electroniccontroller to cause the electronic controller to adjust the secondviewing angle.

In response to determining that viewing angle adjustment data has beenreceived, the LED display generates, with an electronic controller, anangle adjustment command using the viewing angle adjustment data (1008).For instance, the electronic controller determines, for each of thedirectional light emitters, an angle adjustment command using theviewing angle adjustment data. The angle adjustment command may includea separate command for each directional light emitter, a separatecommand for groups of directional light emitters, or a command for allof the directional light emitters. A group of directional light emittersmay include a pixel subset, a color specific pixel sub-subset, or adirectional pixel sub-subset.

The LED display adjusts one or more light directing elements using theangle adjustment command (1010). For example, the electronic controllermay provide the angle adjustment command to one or more light directingelements to cause the light directing elements to adjust the secondviewing angle for the second display image, e.g., the directionaldisplay image.

The electronic controller may include the one or more light directingelements. The electronic controller may include one light directingelement for each directional light emitter. The electronic controllermay include one light directing element for each group of directionallight emitters, e.g., for each pixel subset, each color specific pixelsub-subset, or each directional pixel sub-subset. In some examples, theelectronic controller may include a single light directing element forall of the directional light emitters.

In response to determining that viewing angle adjustment data has notbeen received, the LED display maintains a current position of one ormore light directing elements (1012). For instance, the LED displaydetermines to maintain the second viewing angle for the second displayimage, generated by the directional light emitters, when the LED displaydoes not receive any viewing angle adjustment data. The LED display maydetermine to maintain a current position of all of the one or more lightdirecting elements.

The order of steps in the process 1000 described above is illustrativeonly, and generating the two overlaid images using the correspondingwide-angle and directional light emitters can be performed in differentorders. For example, the LED display may generate the second displayimage and then generate the first display image. In some examples, theLED display may begin to generate the first display image atsubstantially the same time that the LED display begins to generate thesecond display image.

In some implementations, the process 1000 can include additional steps,fewer steps, or some of the steps can be divided into multiple steps.For example, the LED display may perform steps 1002, 1004, and 1012without performing steps 1006-1010.

As noted previously, the disclosed displays are controlled by anelectronic controller that delivers signals to each subpixelcoordinating their operation to so that the display displays the desiredimages or light fields. In general, components of the electroniccontroller can be housed in the same housing as the display panel and/orcan be contained in a separate housing.

Components of an electronic controller for a display 1100 are shownschematically in FIG. 11, which includes a display 1101 composed ofpixels 1130, device drivers 1180 for pixels 1130, and device electronics1120. Electronics 1120 includes a bus 1124, which servers to communicatedata between other components of the device electronics and devicedrivers 1180. Bus 1124 is illustrated as a single bus for simplicity,but may represent multiple different interconnects or buses and thecomponent connections to such interconnects or buses may vary.

Device electronics 1120 includes a processor 1110 coupled to bus 1124,to provide control instructions for the display. Generally, processor430 can include one or more processors or controllers, including one ormore physical processors and one or more logical processors.General-purpose processors and/or special-processor processors can beused.

Electronics 1120 further includes a random access memory (RAM) or otherdynamic storage device or element as a main memory 1132 for storinginformation and instructions to be executed by processor 1110.Electronics 1120 also includes a non-volatile memory 1134 and a readonly memory (ROM) 1136 or other static storage device for storing staticinformation and instructions for the processor.

Electronics 1120 also includes one or more transmitters or receivers1140 coupled to bus 1124, as well as one or more antenna(e) 1144 and oneor more port(s) 1142. Antennae 1144 can include dipole or monopoleantennae, for the transmission and reception of data via wirelesscommunication using a wireless transmitter, receiver, or both. Ports1142 are used for the transmission and reception of data via wiredcommunications. Wireless communication includes, but is not limited to,Wi-Fi, Bluetooth™, near field communication, and other wirelesscommunication standards. Wired communication includes, but is notlimited to, USB® (Universal Serial Bus) and FireWire® ports.

Device electronics 1120 can also include a battery or other power source1150, which may include a solar cell, a fuel cell, a charged capacitor,near field inductive coupling, or other system or device for providingor generating power in the supporting electronics 1120. The powerprovided by power source 1150 may be distributed as required to elementsof the electronics 1120.

In some embodiments, the foregoing displays are interfaced with or formpart of a computer system. FIG. 12 is a schematic diagram of an examplecomputer system 1200. The system 1200 can be used to carry out theoperations described in association the implementations describedpreviously (e.g., those of controller 120). In some implementations,computing systems and devices and the functional operations describedabove can be implemented in digital electronic circuitry, intangibly-embodied computer software or firmware, in computer hardware,including the structures disclosed in this specification (e.g., system1200) and their structural equivalents, or in combinations of one ormore of them. The system 1200 is intended to include various forms ofdigital computers, such as laptops, desktops, workstations, personaldigital assistants, servers, blade servers, mainframes, and otherappropriate computers, including vehicles installed on base units or podunits of modular vehicles. The system 1200 can also include mobiledevices, such as personal digital assistants, cellular telephones,smartphones, and other similar computing devices. Additionally, thesystem can include portable storage media, such as, Universal Serial Bus(USB) flash drives. For example, the USB flash drives may storeoperating systems and other applications. The USB flash drives caninclude input/output components, such as a wireless transmitter or USBconnector that may be inserted into a USB port of another computingdevice.

The system 1200 includes a processor 1210, a memory 1220, a storagedevice 1230, and an input/output device 1240. Each of the components1210, 1220, 1230, and 1240 are interconnected using a system bus 1250.The processor 1210 is capable of processing instructions for executionwithin the system 1200. The processor may be designed using any of anumber of architectures. For example, the processor 1210 may be a CISC(Complex Instruction Set Computers) processor, a RISC (ReducedInstruction Set Computer) processor, or a MISC (Minimal Instruction SetComputer) processor.

In one implementation, the processor 1210 is a single-threadedprocessor. In another implementation, the processor 1210 is amulti-threaded processor. The processor 1210 is capable of processinginstructions stored in the memory 1220 or on the storage device 1230 todisplay graphical information for a user interface on the input/outputdevice 1240.

The memory 1220 stores information within the system 1200. In oneimplementation, the memory 1220 is a computer-readable medium. In oneimplementation, the memory 1220 is a volatile memory unit. In anotherimplementation, the memory 1220 is a non-volatile memory unit.

The storage device 1230 is capable of providing mass storage for thesystem 1200. In one implementation, the storage device 1230 is acomputer-readable medium. In various different implementations, thestorage device 1230 may be a floppy disk device, a hard disk device, anoptical disk device, or a tape device.

The input/output device 1240 provides input/output operations for thesystem 1200. In one implementation, the input/output device 1240includes a keyboard and/or pointing device. In another implementation,the input/output device 1240 includes a display unit for displayinggraphical user interfaces.

The features described can be implemented in digital electroniccircuitry, or in computer hardware, firmware, software, or incombinations of them. The apparatus can be implemented in a computerprogram product tangibly embodied in an information carrier, e.g., in amachine-readable storage device for execution by a programmableprocessor; and method steps can be performed by a programmable processorexecuting a program of instructions to perform functions of thedescribed implementations by operating on input data and generatingoutput. The described features can be implemented advantageously in oneor more computer programs that are executable on a programmable systemincluding at least one programmable processor coupled to receive dataand instructions from, and to transmit data and instructions to, a datastorage system, at least one input device, and at least one outputdevice. A computer program is a set of instructions that can be used,directly or indirectly, in a computer to perform a certain activity orbring about a certain result. A computer program can be written in anyform of programming language, including compiled or interpretedlanguages, and it can be deployed in any form, including as astand-alone program or as a module, component, subroutine, or other unitsuitable for use in a computing environment.

Suitable processors for the execution of a program of instructionsinclude, by way of example, both general and special purposemicroprocessors, and the sole processor or one of multiple processors ofany kind of computer. Generally, a processor will receive instructionsand data from a read-only memory or a random access memory or both. Theessential elements of a computer are a processor for executinginstructions and one or more memories for storing instructions and data.Generally, a computer will also include, or be operatively coupled tocommunicate with, one or more mass storage devices for storing datafiles; such devices include magnetic disks, such as internal hard disksand removable disks; magneto-optical disks; and optical disks. Storagedevices suitable for tangibly embodying computer program instructionsand data include all forms of non-volatile memory, including by way ofexample semiconductor memory devices, such as EPROM, EEPROM, and flashmemory devices; magnetic disks such as internal hard disks and removabledisks; magneto-optical disks; and CD-ROM and DVD-ROM disks. Theprocessor and the memory can be supplemented by, or incorporated in,ASICs (application-specific integrated circuits).

To provide for interaction with a user, the features can be implementedon a computer having a display such as a CRT (cathode ray tube) or LCD(liquid crystal display) monitor for displaying information to the userand a keyboard and a pointing device such as a mouse or a trackball bywhich the user can provide input to the computer. Additionally, suchactivities can be implemented via touchscreen flat-panel displays andother appropriate mechanisms.

The features can be implemented in a computer system that includes aback-end component, such as a data server, or that includes a middlewarecomponent, such as an application server or an Internet server, or thatincludes a front-end component, such as a client computer having agraphical user interface or an Internet browser, or any combination ofthem. The components of the system can be connected by any form ormedium of digital data communication such as a communication network.Examples of communication networks include a local area network (“LAN”),a wide area network (“WAN”), peer-to-peer networks (having ad-hoc orstatic members), grid computing infrastructures, and the Internet.

The computer system can include clients and servers. A client and serverare generally remote from each other and typically interact through anetwork, such as the described one. The relationship of client andserver arises by virtue of computer programs running on the respectivecomputers and having a client-server relationship to each other.

As used herein, the term “perpendicular” refers to a relationshipbetween two elements (e.g., lines, axes, planes, surfaces, orcomponents) forming approximately a 90° angle within acceptableengineering, fabrication, or measurement tolerances as understood bysomeone of ordinary skill in the art.

While this specification contains many specific implementation details,these should not be construed as limitations on the scope of anyinventions or of what may be claimed, but rather as descriptions offeatures specific to particular implementations of particularinventions. Certain features that are described in this specification inthe context of separate implementations can also be implemented incombination in a single implementation. Conversely, various featuresthat are described in the context of a single implementation can also beimplemented in multiple implementations separately or in any suitablesubcombination. Moreover, although features may be described above asacting in certain combinations and even initially claimed as such, oneor more features from a claimed combination can in some cases be excisedfrom the combination, and the claimed combination may be directed to asubcombination or variation of a subcombination.

Similarly, while operations are depicted in the drawings in a particularorder, this should not be understood as requiring that such operationsbe performed in the particular order shown or in sequential order, orthat all illustrated operations be performed, to achieve desirableresults. In certain circumstances, multitasking and parallel processingmay be advantageous. Moreover, the separation of various systemcomponents in the implementations described above should not beunderstood as requiring such separation in all implementations, and itshould be understood that the described program components and systemscan generally be integrated together in a single software product orpackaged into multiple software products.

Thus, particular implementations of the subject matter have beendescribed. Other implementations are within the scope of the followingclaims. For example, while the foregoing displays are depicted as directview displays (e.g., televisions or computer monitors), otherimplementations are possible. For instance, the disclosed technologiescan be implemented in displays for handheld devices, automotivedisplays, wearable displays (e.g., head mounted displays), and/oravionic displays (e.g., either in cockpit displays or in-flightentertainment systems).

What is claimed is:
 1. A light emitting diode display comprising: anarray of pixels, each pixel comprising at least one directional lightemitter and at least one wide-angle light emitter, a first combinationof all the directional light emitters configured to generate a firstdisplay image viewable within a first viewing angle, and a secondcombination of all the wide-angle light emitters configured to generate,concurrently with the generation of the first display image, a seconddisplay image that a) is a different image than the first display image,b) is viewable within a second viewing angle that is wider than andencompasses the first viewing angle, and c) creates, within the firstviewing angle, an overlaid image from the combination of the firstdisplay image and the second display image; an electronic controller togenerate a signal that causes the light emitting diode display to changea viewing angle for the directional light emitters; and an eye-trackingcomponent to determine eye movement data for a viewer, generate viewingangle adjustment data, and provide the viewing angle adjustment data tothe electronic controller to change the viewing angle of the directionallight emitters.
 2. The light emitting diode display of claim 1, whereinthe eye-tracking component comprising: a camera configured to captureone or more images to record eye movement of the viewer; a processorconfigured to analyze the captured image or video and generate viewingangle adjustment data based on the analysis result; and a communicationunit communicated to the electronic controller and configured totransmit the viewing angle adjustment data to the electronic controller.3. The light emitting diode display of claim 1, wherein the viewingangle adjustment data comprises: a change of the viewing angle of one ormore of the directional light emitters; adjustments for each of thedirectional light emitters; adjustments that apply to groups of two ormore directional light emitters; and a single adjustment that applies toall of the directional light emitters.
 4. The light emitting diodedisplay of claim 1, wherein the array of pixels comprises groups ofviewing angle specific sub-pixels, each of the viewing angle specificsub-pixels comprises a light emitter specific to the correspondingviewing angle.
 5. The light emitting diode display of claim 1, whereinthe viewing angle is an angle at which the display projects light fromthe directional light emitters, wherein the eye-tracking componentdetermines a predicted angle at which the viewer is looking at the lightemitting diode display, and wherein the predicted angle is used todetermine the viewing angle adjustment data.
 6. The light emitting diodedisplay of claim 1, further comprising a communication module to receiveviewing angle adjustment data and provide the viewing angle adjustmentdata to the electronic controller.
 7. The light emitting diode displayof claim 1, wherein the generating of the viewing angle adjustment datacomprises: capturing, by a camera, one or more images; and determining,by the eye-tracking component, the viewing angle adjustment data usingthe one or more images.
 8. The light emitting diode display of claim 1,wherein the eye-tracking component is configured to: adjust narrowviewing angle for a particular viewer by following movement of theparticular viewer; and reduce a likelihood that other viewers can viewthe narrow viewing angle content.
 9. The light emitting diode display ofclaim 1, wherein the electronic controller comprises an array ofcontrollable light directing elements.
 10. The light emitting diodedisplay of claim 9, wherein the electronic controller comprises onelight directing element for each of the directional light emitters. 11.The light emitting diode display of claim 9, wherein the electroniccontroller comprises one light directing element for each group of thedirectional light emitters.
 12. A method comprising: generating, by alight emitting diode display using a plurality of wide-angle emitters, afirst display image viewable in a first viewing angle; and generating,by the display using a plurality of directional emitters concurrentlywith generation of the first display image, a second display image thata) is a different image than the first display image, b) is viewablewithin a second viewing angle that is wider than and encompasses thefirst viewing angle, and c) creates, within the first viewing angle, anoverlaid image from the combination of the first display image and thesecond display image; tracking eye movement of a viewer using aneye-tracking component; determining viewing angle adjustment data basedon the eye movement of the viewer; and generating, by an electroniccontroller, angle adjustment commands using the viewing angle adjustmentdata, wherein changing, by the electronic controller, the second viewingangle of the second display image comprises adjusting, by the electroniccontroller, one or more light directing elements using the angleadjustment commands.
 13. The method of claim 12, wherein the trackingeye movement of a viewer comprising: capturing, by a camera, one or moreimages to record eye movement of the viewer; analyzing, by a processor,the captured images; generating, by the processor, viewing angleadjustment data based on the analysis result; and transmitting, by acommunication unit, the viewing angle adjustment data to the electroniccontroller.
 14. The method of claim 12, wherein generating, by thedisplay using the plurality of directional emitters concurrently withgeneration of the first display image, the second display imagecomprises generating, by the display using the plurality of directionalemitters after generation of the first display image, the second displayimage for presentation concurrently with presentation of the firstdisplay image.
 15. The method of claim 12, further comprising:determining, by the eye-tracking component, a predicted angle at which aviewer is looking at the light emitting diode display; and determiningthe viewing angle adjustment data by using the predicted angle.
 16. Themethod of claim 12, further comprising: receiving, by a communicationmodule, the viewing angle adjustment data; and providing the viewingangle adjustment data to the electronic controller.
 17. The method ofclaim 12, wherein the determining viewing angle adjustment datacomprises: determining, by the eye-tracking component, the viewing angleadjustment data using the one or more images.
 18. The method of claim12, further comprising: adjusting narrow viewing angle for a particularviewer by following movement of the particular viewer; and reducing alikelihood that other viewers can view the narrow viewing angle content.19. The method of claim 12, further comprising: changing, by the displayusing an electronic controller, the second viewing angle of the seconddisplay image.
 20. The method of claim 19, wherein changing the secondviewing angle of the second display image comprising adjusting, by theelectronic controller, one or more light directing elements to changethe second viewing angle of the second display image.